Laser-scanner based bar code reader systems have been in use for some time. These scanners typically comprise a housing having a laser and associated optics therein. Such a laser and associated optics are disclosed, for example, in U.S. Pat. No. 5,200,597, issued to Jay Eastman, et al., on Apr. 6, 1993 and hereby incorporated by reference, wherein the laser is integrated together with electronics on a "scan engine" comprising a printed circuit board. The housing is typically a closed structure which supports, among other components, the laser which produces light to scan the target, and the photodetector which receives light returned from the scanned target. Again typically, the housing has at least one optical window. Light from the laser is optically directed to exit this window, and light returned from the scanned bar code enters this window and is directed toward the photodetector. Thus, the performance of the scanner is in many respects dependent on this window. The window must be quite light transmissive, and hard enough to resist damage. Unfortunately, during ordinary scanner operation, the window may become damaged and require replacement. In known scanner systems of the prior art, the window could only be replaced by disassembling the unit, and reconstructing the housing, and reassembling the scanner.
No presently known bar code scanner features a field replaceable window. Yet other devices have field replaceable windows. None of the existing designs of the prior art suggest even the possibility, let alone how, a field replaceable window could be incorporated in a bar code scanner.
Upgrading a window, too, would be desirable. It may, for example, be desirable to upgrade a bar code window to a "Brewster Scanner Window" of the type disclosed in a patent application Ser. No. 08/059,045 filed on May 7, 1993 entitled Brewster Window Bar Code Scanner in the name of Edward Coleman, et al and assigned to the present assignee.
It may also be desirable to add other optical elements or functions to the scanner. For example, a filter, or special anti-scratch coating might be desirable in one environment, and coated optics in another environment.
A lens cap having a window therein is shown in U.S. Pat. No. 5,162,942, issued to Anzig, et. al. The lens cap window features an interior transparent pane, and an exterior semitransparent (e.g. merely translucent) pane, with a gap known as a title inserting portion between the two panes. (Col. 5, lines 50-65) Into this title insertion portion is placed a "title recording paper" upon which desired screen titles are written for easy photographing in macro or close-up fashion.
A seal assembly for covering an indicator light opening in a control panel is shown in U.S. Pat. No. 3,587,184, issued to Walker. In Walker, an elastomeric seal covers the entirety of the opening, and a window is inserted into an integral lip on the outside of that window. The elastomeric seal, unlike that of the present invention, covers the entire opening.
Bengtsson, in U.S. Pat. No. 5,187,354, discloses an hand scanner for reading bar codes and deactivating surveillance tags, which uses a "rubber cuff or sleeve" to hold permanent magnets about the periphery of an opening in the housing. (Col. 2, lines 29-35). Bengtsson does not teach anything about securing a window about the opening of a scanner.
U.S. Pat. No. 5,177,347, issued to Wike, states "a scanning unit 26 is mounted within the main body portion 24 by means of a support ring 28 which, in addition to supporting the scanning unit 26, also supports a cover member 30 having an opening 32 in which is positioned the face portion 34 of the scanning unit 26. The cover member 30 may be constructed of a transparent material such as acrylic and is shock mounted with respect to the face portion 34 by means of a ring of elastic foam material 36." (Col. 2, line 65 to Col. 3, line 6).
Unlike the present invention the cover in Wike does not support a window. Instead that the cover is supported by a ring. This ring on the main body supports, on one side, the cover with an opening therein, and the same ring supports, on the other side, the scan unit having a window-like! face 34 thereon. Thus, the cover is supported by the same structure as the face; unlike in the present invention, the cover itself does not support the face. Thus, changing the cover of Wike does not afford any easy way of changing any optical element of Wike. Thus, Wike does not teach the present invention.
U.S. Pat. No. 5,165,782, to Maglica et al. discloses a "Shock absorbing lens holder and anti-roll device" for a flashlight; it teaches a way of holding a filter in front of the flashlight lens. This patent does not teach the apparatus of the present invention, which is composed entirely of shock absorbing material, and which requires no further frame, anti-roll or otherwise, to hold it in place. Furthermore, Maglica's apparatus requires that it be mounted on a flashlight already having a sealed lens; the present invention provides what may be a lens, or window, and mounts directly on the scanner.